1. Technical Field
The present invention relates to a pattern formation device.
2. Related Art
An inkjet device, i.e., a droplet discharge device for forming and discharging functional liquid as droplets is generally known as a device for forming a desired pattern on a substrate using the functional liquid. The droplet discharge device forms a pattern by depositing droplets of functional liquid discharged from a droplet discharge head in arbitrary locations on a substrate while the substrate mounted on a stage and the droplet discharge head for forming and discharging functional liquid as droplets is moved in a relative fashion in a two-dimensional direction.
A functional liquid is supplied from a separately disposed tank, and the droplet discharge head temporarily stores the functional liquid thus supplied in an internally disposed ink chamber (cavity). The functional liquid stored in the ink chamber is formed into droplets and discharged from a large number of nozzle holes formed in a nozzle plate that is disposed so as to face the stage.
In recent years, multiple-carriage-type droplet discharge devices are known in which a plurality of droplet discharge heads is mounted on a single carriage and a plurality of such carriages is mounted on the device. Such a droplet discharge device is used in manufacturing large-screen color filters and in other applications, and the drawing speed is improved by simultaneously discharging droplets from the plurality of carriages.
When the droplet discharge device is forming a pattern on the substrate, a platen gap, which is a space between the droplet discharge head and the nozzle plate, is very small, e.g., 0.3 mm. Therefore, various problems occur when dust or other foreign matter is deposited on the substrate. An example of such a problem is that the foreign matter comes into contact with the droplet discharge head when foreign matter is deposited on the upper surface of the substrate mounted on the stage, and the substrate and droplet discharge head are damaged. Another example of such a problem is that the substrate in the area where the foreign matter is deposited on the lower surface of the substrate increase in height in relation to the stage, the substrate and the droplet discharge head make contact, and the substrate is damaged.
Japanese Laid-open Patent Application No. 2007-85960 discloses a foreign matter detection device that proposes a method for solving such problems, wherein a light projecting unit and a light receiving unit are provided, a substrate is passed between the light projecting unit and the light receiving unit, detection light emitted from the light projecting unit along the upper surface of the substrate is received by the light receiving unit, and foreign matter deposited on the substrate is detected based on the amount of light received by the light receiving unit.